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2 questions: Update parentcolumn and return identity

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doggelito

Post subject: 2 questions: Update parentcolumn and return identity

Posted: Thu Jan 24, 2008 9:43 am

Beginner

Joined: Mon Jan 14, 2008 10:58 am
Posts: 24

I'm sorry but I don't understand! :(
Map file:

Code:

<class name="Swh.Entities.Category, Swh.Entities" table="Categories">
      <id name="Id" column="CategoryId" type="int" unsaved-value="0">
         <generator class="identity" />
      </id>
      <many-to-one name="Parent" column="ParentId" />   
      <property name="Name" column="CategoryName" type="String"/>
   </class>

Pretty simple, one category that has a parent category.

Question 1:
Now I want to make an update like this:

Code:

...
ITransaction transaction = CurrentSession.BeginTransaction();
Category cat = new Category();
cat.Id = 12345;
cat.Name = "test";
cat.ParentId = 54321; [b]How should this line look like?[/b]
//cat.Parent.Id = 54321; 
CurrentSession.SaveOrUpdate(cat);
transaction.Commit();

The column in the database is ParentId.
Can't I use the Parent relation mapping for this? Do I have to add a property named ParentId to my map?

Question 2:
How do I return the primary key from an category insert?

Code:

ITransaction transaction = CurrentSession.BeginTransaction();
Category cat = new Category();
cat.Name = "test2";
//cat.ParentId = 54321;
int Id = CurrentSession.SaveOrUpdate(cat); [b]How should this line look like?[/b]
transaction.Commit();

I guess stupid simple questions but I can't find the answers in other threads!

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doggelito

Post subject:

Posted: Thu Jan 24, 2008 10:16 am

Beginner

Joined: Mon Jan 14, 2008 10:58 am
Posts: 24

Hmm, one solved, one to go!

Returning identity was (as I thought) simple!

Code:

ITransaction transaction = CurrentSession.BeginTransaction();
Category cat = new Category();
cat.Name = "test2";
CurrentSession.Save(cat);
transaction.Commit();
int id = cat.Id;

NHibernate adds the id automaticly for me to my class! :)

So, what about updating the parentid? How do I solve that?
I tried to add a property field to the map file like

Code:

<class name="Swh.Entities.Category, Swh.Entities" table="Categories">
      <id name="Id" column="CategoryId" type="int" unsaved-value="0">
         <generator class="identity" />
      </id>
      <many-to-one name="Parent" column="ParentId" />   
      <property name="ParentId" column="ParentId" type="int"/>
      <property name="Name" column="CategoryName" type="String"/>
   </class> 

But then I just get an error saying I got duplicate columns! :(

I also tried this:

Code:

ITransaction transaction = CurrentSession.BeginTransaction();
Category cat = new Category();
cat.Id = 12345;
cat.Name = "test";
cat.Parent.Id = 54321;
CurrentSession.SaveOrUpdate(cat);
transaction.Commit(); 

But then I just got "Object reference not set to an instance of an object" on the cat.Parent.Id line.

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kev160967

Post subject:

Posted: Thu Jan 24, 2008 10:35 am

Beginner

Joined: Sun Nov 18, 2007 10:39 am
Posts: 46
Location: Liverpool, England

Fetch the parent object, then assign it to the parent property in the child

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doggelito

Post subject:

Posted: Fri Jan 25, 2008 6:57 am

Beginner

Joined: Mon Jan 14, 2008 10:58 am
Posts: 24

Ahh, thanks kev! :)

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